Pliers are a two-legged tool where the effective spots are pressed against each other. Basically, pliers consist of three components, i.e. the handles, the joint and they pliers head. They operate according to the lever principle. Two two-sided levers are interconnected by a joint. Usually the handles form the longer lever arms; the shorter lever arms form the pliers head. The manual power affected on the handles is amplified according to the law of the lever and transferred to the work piece by means of the pliers head.
Pliers related to by the present invention are used in various applications and especially used in the form of water pump pliers. Water pump pliers are gripping pliers, with an adjustable sliding joint, so that opening widths of the opening can be adjusted in various sizes. They are mainly used for gripping pipes, bushings and screws/nuts of different kinds, but also for flats etc.
Key pliers are known from the European Patent specification EP 0 421 107. Key pliers with two pliers jaws forming the pliers opening are described in this publication. One of the pliers jaws tightly abuts a pliers arm which is provided with a longitudinal slot guiding for a pliers leg pivot pin to roughly adjust the pliers opening. A fork-shaped, movable jaw for encompassing the fixed pliers leg is shiftably guided in a guiding groove at the pliers leg carrying the fixed pliers jaw. A power transmission spot between a shoulder of the shiftable pliers jaw and the jaw-side arm of the movable pliers leg is adapted to be displaced to close the pliers opening. The power transmission spot in the form of a form-fit engagement between the jaw-side arm and the movable pliers jaw is the interconnecting spot for the rough longitudinal adjustment as well as for the closing of the pliers opening between the pliers leg and the movable jaw.
The US patent specification U.S. Pat. No. 3,534,641 discloses a pliers consisting of two gripper arms. A first pliers jaw is integrated in a first gripper arm. A second pliers jaw is shiftably arranged on one side of the first gripper arm. For this purpose the first gripper arm is provided with a section with an abutment surface perpendicular to the pivot axis of the pliers. The second pliers jaw is designed to encompass the abutment surface of the first gripper arm with a groove-shaped abutment surface. Furthermore, a detent slot is provided in the first gripper arm wherein a pivot pin in the form of a screw is provided, the pivot pin having a detent mechanism. The second gripper arm engages the second movable pliers jaw at this pivot pin for the power transmission. While the second gripper arm is arranged on the one side of the first gripper arm the second pliers jaw is correspondingly provided on the opposite side of the first gripper arm. The second gripper arm can be adjusted with the second pliers jaw in the detent slot for rough adjustment. By activating the pliers the second pliers jaw is shifted along the section for power transmission according to the lever path.
The known pliers have the disadvantage, that they have many spots, where a user can pinch himself during gripping, for example at the rough adjustment of the pliers.